Tankless electric water heater

Abstract

A tankless electric water heater system including a heating chamber having an inlet at a first end and an outlet at a second end, a heating element connected to the heating chamber, a first temperature sensor disposed near the first end of the heating chamber, a second temperature sensor disposed near the second end of the heating chamber, a flow sensor configured to detect a flow of water and disposed near the heating chamber, and a controller connected to the first and second temperature sensors, the flow sensor, and the heating element. The controller is configured to have a set point temperature, to detect temperature and flow data from the first and second temperature sensors, and the flow sensor, and to provide as output a power setting to the heating element.

What is claimed is: 
     
       1. A fluid heating device comprising:
 an inlet; 
 an outlet; 
 a heating chamber disposed between the inlet and the outlet; 
 a heating element disposed inside the heating chamber; 
 a flow sensor disposed between the inlet and the heating chamber and configured to detect a flow rate of liquid flowing from the inlet; 
 a valve disposed between the heating chamber and the outlet; 
 a first temperature sensor configured to detect a first temperature of the fluid between the heating chamber and the valve; 
 a second temperature sensor configured to detect a second temperature of fluid downstream of the inlet; and 
 a controller configured to maintain the fluid at a predetermined temperature by
 regulating a supply of power to the heating element as a function of the first temperature, the second temperature and the flow rate, and 
 adjusting an amount at which the valve is opened as a function of the first temperature, the second temperature and the flow rate. 
 
 
     
     
       2. The fluid heating device of  claim 1 , further comprising:
 a first conduit connecting the inlet to the heating chamber, 
 wherein a flow path exists from the inlet to the heating chamber via the first conduit and out of the fluid heating device via the outlet. 
 
     
     
       3. The fluid heating device of  claim 2 , further comprising:
 a second conduit connected to the first conduit; and 
 a third conduit connected to the second conduit, 
 wherein the heating chamber includes a first inlet connected to the third conduit. 
 
     
     
       4. The fluid heating device of  claim 3 , further comprising: a fourth conduit connected to the second conduit,
 wherein the heating chamber includes a second inlet connected to the fourth conduit. 
 
     
     
       5. The fluid heating device of  claim 4 , wherein a flow path exists from the inlet to the heating chamber via the first, second, third and fourth conduits. 
     
     
       6. The fluid heating device of  claim 1 , wherein the controller is configured to proportionally control the valve to limit flow of the liquid until the first temperature is at a predetermined value. 
     
     
       7. The fluid heating device of  claim 1 , wherein the second temperature sensor is disposed between the inlet and the flow sensor. 
     
     
       8. The fluid heating device of  claim 1 , wherein the flow sensor is disposed between the second temperature sensor and a conduit connecting the inlet to the heating chamber. 
     
     
       9. The fluid heating device of  claim 1 , further comprising:
 a housing to house the heating chamber, the first temperature sensor and the flow sensor. 
 
     
     
       10. The fluid heating device of  claim 1 , further comprising:
 a display screen to display settings of the fluid heating device, and 
 an input to adjust the settings of the fluid heating device. 
 
     
     
       11. The fluid heating device of  claim 1 , wherein the controller controls the valve to prevent fluid from exiting the fluid heating device by closing the outlet when the first temperature is above a predetermined set point. 
     
     
       12. The fluid heating device of  claim 1 , wherein the controller controls the valve to prevent fluid from exiting the fluid heating device by closing the outlet when the first temperature is below a predetermined set point. 
     
     
       13. A system comprising:
 a liquid storage device; 
 an inlet pipe connected to an outlet of the liquid storage device; and 
 a fluid heating device having
 an inlet connected to the inlet pipe, 
 an outlet, 
 a heating chamber disposed between the inlet and the outlet, 
 a heating element disposed inside the heating chamber, 
 a flow sensor disposed between the inlet and the heating chamber and configured to detect a flow rate of liquid flowing from the inlet, 
 a valve disposed between the heating chamber and the outlet, 
 a first temperature sensor configured to detect a first temperature of the fluid between the heating chamber and the valve, 
 a second temperature sensor configured to detect a second temperature of fluid downstream of the inlet, 
 a controller configured to maintain the fluid at a predetermined temperature by
 regulating a supply of power to the heating element as a function the first temperature, the second temperature and the flow rate, and 
 adjusting an amount at which the valve is opened as a function of the first temperature, the second temperature and the flow rate. 
 
 
 
     
     
       14. The system according to  claim 13 , wherein
 the liquid storage device includes
 a first power supply, and 
 a liquid storage device heating element, and 
 
 the fluid heating device further includes
 a second power supply, and 
 a switch connected to the first power supply and the second power supply, 
 wherein the controller is configured to control the switch to switch between providing a supply of power to the liquid storage device heating element via the first power supply or providing a supply of power to the heating element via the second power supply. 
 
 
     
     
       15. The system according to  claim 13 , further comprising:
 a second inlet pipe connected to the liquid storage device; 
 a recirculation pipe connected to the fluid heating device and the second inlet pipe; and 
 a recirculation pump, 
 wherein the controller is configured to control the recirculation pump to recirculate fluid from the fluid heating device to the liquid storage device via the recirculation pipe. 
 
     
     
       16. The system according to  claim 15 , wherein the recirculation pipe is connected to the fluid heating device upstream of the heating element. 
     
     
       17. The system according to  claim 15 , wherein the recirculation pipe is connected to the fluid heating device downstream of the heating element. 
     
     
       18. The system according to  claim 15 , further comprising:
 an inlet proportioning valve connected to the second inlet pipe, 
 wherein the controller is configured to control the inlet proportioning valve to control fluid temperature and flow.